There has been a heightened awareness of the dangers of plastics, with a focus on how they may harm the environment and our bodies.

Have you noticed the water from a bottle left in a warm car or in the sun tasting different? That change in flavor is a change to the chemical compound of that water, according to scientists.

Emanuela Gionfriddo is an associate professor in the Department of Chemistry at the University at Buffalo. Gionfriddo explains as plastic water bottles heat up from the sun, or are left in a hot car, they start to leach chemicals.

The bottles are made from chemicals known as PET. They're safe for conventional storage conditions. But when they are exposed to ultraviolet rays, some of the building blocks of these plastics start to break down and leach.

The extent of these chemicals in the water from plastic bottles depends on many factors, such as how long the bottle has been exposed to the sun and warmth. The good news is a few hours isn’t enough to make water toxic.

Most of us have likely heard of the push for BPA-free water bottles. But does that make a difference?

“If they don't contain BPA, then they can leach something else," said Gionfriddo. "So it's never a good idea to leave plastic bottles under the sun and high temperature for a long period of time, because those are not the conditions these plastic were tested for.”

Gionfriddo says soda enhances the process because it has a lower PH level. Stainless steel and glass water bottles are again the best option.

Something else to consider is bacterial growth. Bacteria thrives in warmer temperatures.

Cold water is best. Doctors say cool water will help your body’s temperature stay regulated as it works overtime on a hot summer day.